A manufacturer needs a quote to start with the fabrication or assembly of a circuit board. A quote plays an important role in PCB assembly. Therefore, most manufacturers request it before they commence with their task. A PCB quote provides an estimate of what it costs to manufacture a circuit board. However, in this article, we will be discussing SMT assembly quotes.
What is an SMT Assembly Quote?
An SMT assembly quote is an estimate that reveals the cost and time needed to transform an SMT design into a board. Once the design of an SMT assembly is ready, the next step is manufacturing. However, before the manufacturing commences, an SMT quote is necessary. A manufacturer will fabricate an accurate PCB if there are vital details about the board.
A quote is widely used in SMT assembly. An accurate SMT quote is necessary to achieve an effective SMT assembly. An SMT quote doesn’t just provide information about the cost of assembling a circuit board. It also gives details about the capabilities and time requirements for the assembly.
The accuracy of an SMT quote makes manufacturing easier. Therefore, it is very important to feature the necessary information in the quote. If vital information isn’t included, the SMT assembler will contact the designer. However, this might make the assembly process take a longer time.
An SMT assembly quote includes pieces of information like:
- Board type
- Quantity
- Number of unique parts
- The number of SMD parts
- Number of board layers
- Type of surface finish
- Individual board dimensions
- Boards per package
- Required time for placing an SMT part
- Total cost of processing
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Other Facts about SMT Assembly Quote
Files needed for SMT Assembly Quote
When requesting an SMT quote, you will need some assembly files. These files include BOM, Gerber/ODB++, and CPL files.
BOM
The BOM file is an important document for SMT manufacturing and assembly. This file helps the SMT manufacturer have an estimate of the components’ prices.
Gerber/ODB++
This file is crucial for SMT assembly. It offers important details as regards every layer of the circuit board.
CPL file
The component placement list file is very important for the SMT assembly quote. This file helps the SMT assembly machine to know where to locate on the board.
Frequently missed details during the request for an SMT Quote
Some designers may miss out some important details in an SMT quote. These details help to calculate the time estimate and total cost of SMT assembly. Some missed information on the SMT quote include;
Silkscreen details
Sometimes, the designer doesn’t pay attention to the silkscreen details. It is important to provide details about the color of the silkscreen. Also, determine if the silkscreen will be on both sides.
Stack-up details
You should include the order of the layers, the number of layers, and more in the SMT quote. Ensure you don’t miss any details as regards the stack-up.
Solder Mask details
You should include the type, color, finish, and sides of the solder mask in the SMT assembly quote.
Impedance details
The selection of different parameters will depend on the impedance requirements of a PCB.
Factors that Influences SMT Assembly Cost
Several factors determine the cost of SMT assembly. When a designer prepares an SMT quote, the assembler needs to look into this quote. This is important to confirm if the budget in the quote aligns with the cost of assembly. Factors like technology, cost of labor, amount of PCB, and more can influence the cost of assembly.
Parts packaging
SMT assembly is a vital aspect in the fabrication of modern circuit boards. Its exceptional performance helps to produce great and simple-to-manufacture devices. However, some SMT parts need better assembly and can be labor demanding.
Turnaround time
This factor describes the time needed to manufacture a board. It encompasses the time frame needed to satisfy a customer’s demands. Faster turnaround time results in the high cost of manufacturing a board. PCB users who request for faster turnaround time will pay more for their SMT assembly.
Quantity
Higher quantities reduce the cost of SMT assembly. This is a result of economies of scale. Therefore, when more products are manufactured, the price of PCB per unit reduces.
Technology
In SMT assembly, various technologies are used. SMT involves the use of automated technologies to place components. Hence, the type of technology used also influences the cost of SMT assembly. However, SMT provides cost-saving ways because automation is involved.
Labor
This factor also influences the cost of SMT assembly. The assembly process encompasses skilled labor and automated machinery. Therefore, the cost of labor is important. However, the location of manufacturing determines the cost of labor.
Benefits of SMT Assembly Quote
SMT assembly quote is of great importance to both the PCB manufacturer and the PCB user. The benefits of submitting a quote to a manufacturer can’t be underestimated. Below are some of the benefits of SMT quotes in PCB manufacturing.
Creates a minimum base rate for manufacturing
Sometimes, unforeseen circumstances may occur. An SMT quote can help to establish a base rate for the task ahead. It can also outline what the rate covers. Therefore, even if a client decides to make some changes, you can refer to the original quote. The quote can then be updated as regards the change.
Helps you estimate a budget
As a PCB manufacturer, you will need to work with an estimated budget. Before you sign up for a job, you need to have a budget. With an SMT quote, you can easily estimate the cost of assembly. An SMT quote provides the cost of manufacturing or assembling a PCB.
Creates a line of communication with potential clients
Sometimes, a potential client will decide that your quote is out of their budget. Regardless, providing a quote creates a healthy relationship with potential clients. This shows how honest and upfront you are in your job.
Helps you have a breakdown of what you need
One great benefit of using a quote is that it provides the number of parts needed for SMT assembly. The quote allows you to have a breakdown of the items needed for the assembly process. You will need to know the amount of resources, labor, and material needed.
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How to Improve the Accuracy of an SMT Quote
PCB assemblers often receive several requests for quotes. There are now more convenient online quoting formats. However, some customers still prefer the old way of sending quotes through files. The absence of some items in a quote can undermine your efforts as an assembler.
When providing details for online orders, there is a need for accuracy. If you don’t specify the quantity of SMT parts, you might end up getting something else. Some companies provide a quote based on the interpretation of your incomplete details. However, you don’t know how accurate the quote you are being given is.
These companies base their quotation on “least expensive” materials. For example, they quote tin-lead for surface finish. For the type of material, they include low temp FR4 in the quote. They proposed v-scoring without space between for material utilization. When you receive the full drawings and the boards need a gold finish. Also, V-scoring can’t work for the PCB. Then, the company informs you that the cost is more than the initial estimate.
It isn’t a difficult task to ensure your supplier gets accurate information. Therefore, what does a fabricator require to know what you are asking for?
- Gerber files for all layers. This will include solder paste, solder mask, and silkscreen legend.
- If the circuit board will be subjected to automotive, military, or aerospace rules.
- Provide a panel drawing or a description of the number of PCBs on the panel.
- Include fabrication drawing. The drawing must consist of hole sizes and locations, laminate information, and more.
What is SMT Assembly?
SMT assembly involves placing components directly on the surface of a circuit board. It is a modern method of producing electronic circuits. The SMT assembly replaced the through-hole method of manufacturing PCBs. As electronic production advanced, the need for a better process arose. This need gave birth to the SMT assembly.
In SMT assembly, the use of an automated machine is common. The process involves using automation to place electronic components on circuit boards. The use of the pick and place machine is the core of the SMT assembly process. The manufacturer supplies the machine with the necessary components. SMT is commonly used for PCB assembly in today’s world.
SMT assembly helps to reduce the whole size and weight of the circuit board. Therefore, it allows more components in a confined space. This enables PCB assemblers to achieve a reliable and awesome design. The surface mount technology is useful as it enables large-scale PCB manufacturing. SMT is an alternative to the use of leads or wires on circuit boards.
Instead of drilling many holes on the board, SMT involves drilling fewer or no holes. SMT assembly enables the component placement on the two sides of the PCB. Therefore, this enables the production of more powerful and faster integrated chips. SMT assembly is a process that consists of many steps. These steps may vary depending on the application requirement.
SMT assembly involves stenciling, silkscreening, solder masking, and more. Reflow soldering is also an important step in SMT assembly.
Causes of Defects in SMT Assembly
SMT assembly involves several steps. However, they could be errors in these steps. These errors can cause defects in the assembly process.
Placement process defect
The most complicated step in SMT manufacturing is the placement process. The placement level shows the performance of SMT assembly. However, there are defects in this step. The wrong orientation of components may be a result of the mistakes from component suppliers. Incorrect alignment may result in misplacement.
Soldering process defect
The soldering process involves sticking devices to PCB via melting metallic solder. This solder will cool down and be hardened. Defects in soldering can affect the functionality of electronic devices. Assemblers need to consider all important elements when it comes to soldering. Consider the surface cleanness, solder quality, and the temperature setting of the soldering.
Soldering balls can make integrated circuits shorts. This may result in failure in assembled circuits. Also, if smaller circuits are to undergo second soldering, shorts can be triggered on circuit boards. This may be a result of rolling soldering balls.
Solder paste printing process defect
The quality and functionality of a PCB also depend on solder paste printing. If PCB assemblers don’t pay attention during this process, soldering balls can be a problem. For instance, unwetting can make metallic particles have irregular shapes. This is a result of inadequate solder paste. Metallic particles oxidization can trigger soldering balls.
How to Improve SMT Assembly Quality
Having discussed what causes defects in the quality of SMT assembly. It is important to understand that there are measures to help improve SMT assembly quality.
Solder paste printing technology management
Solder paste is crucial in SMT assembly. A large percentage of quality defects in SMT assembly result from improper solder paste printing. Therefore, improving the quality of solder paste printing helps to increase the quality of SMT assembly. There are measures to take to improve solder paste printing technology;
- Improve solder paste quality
Before the use of solder paste, manufacturers should place it at a temperature of 5°C. You should only take it out when it is ready for use in the assembly process. Once there is too much moisture in solder paste, vaporation can cause splashing. This can result in the formation of soldering balls. The maximum solder paste application temperature is 20°C. Therefore it is important to control the temperature of solder paste during assembly.
- Stencil placement
SMT assemblers should correctly place stencils according to markers on the board. Proper alignment parameter setting can increase printing quality.
Soldering Technology management
Reflow soldering also plays a crucial role in the functionality of PCBs. Temperature rising and preheating can control the temperature. This partially volatize melting solder paste.
Placement technology management
This is an important aspect of surface mount technology. As components become miniaturized, SMT assembly needs to tackle increasing complexity. SMT assembly uses a pick and place machine to place components on circuit boards. Placement quality depends on mounting position and component selection. For instance, a chip mounter can help you to achieve component recognition. Too little pressure can result in extreme height of components. On the other hand, solder paste collapse can result from too high pressure.
Conclusion
SMT assembly quote plays a significant role in the assembly process of a PCB. This quote provides important details about the time and cost of an SMT assembly. An SMT quote is both beneficial to the SMT manufacturer and potential clients.
